Iron

Question 1

ferric form

Answer 1

fe3+

Question 2

ferrous form

Answer 2

fe2+

Question 3

where does fe2+ sit in haemoglobin

Answer 3

in prophyrin ring

Question 4

where is the majority of body iron found

Answer 4

in haem

Question 5

wjere does iron absorption mainly occur

Answer 5

duodenum

Question 6

what is iron absorption enhanced by

Answer 6

aacorbic acid- vit c
meat and fish
acidic environment

Question 7

what is iron absorption inhibited by

Answer 7

tannins e.g tea
phytates- cereals, bran nuts and seeds
calcium e.g dairy produce

Question 8

what does cyctochrome b do to iron

Answer 8

reduces feric iron 3+ to ferrous form 2+

Question 9

role of DMT- divalent metal transporter

Answer 9

transports ferrous iron into duodenal enterocyte

Question 10

ferroportin role

Answer 10

facilitates ironn export from enterocyte
passed onto transferrin for transport elsehwere

Question 11

where is ferroportin highly expressed

Answer 11

on basolateral membrane of enterocytes in duodenum where it transports dietary iron absorbed in intestines into bloodstream

Question 12

how is iron absorption regulted

Answer 12

via hepcidin- mjaor negative regulator of iron uptake

Question 13

where is hepcidin produced

Answer 13

in the liver in response to increased iron load and inflammation

Question 14

MOA of hepcidin

Answer 14

binds to ferroportin and causes its degradation

iron therefore trapped in duodenal cells and macrophages

Question 15

when do hepcidin levels decrease

Answer 15

when iron deficient

Question 16

characterisation of iron

Answer 16

functional iron - hb conc

transport iron/ iron supply to tissues- 5 saturation of transfer with iron

storage iron- serum ferritin

Question 17

what is transferrin

Answer 17

a protein with two binding sites for iron atoms

Question 18

role of transferrin

Answer 18

transports iron from donor tissues to tissues expressing transferrin receptors

Question 19

what is especially rich in transferrin

Answer 19

erythroid marrow

Question 20

what measures iron supply

Answer 20

transferrin saturation

Question 21

when also does ferritin go up

Answer 21

with infecti9on, maligancy etc as it is an acute phae protein

Question 22

ferritin

Answer 22

protein which stores and releases iron in the body

spherical intracellular protein stores up to 4000 ferric ions

Question 23

how much iron do we need

Answer 23

4g

Question 24

consequences of negative iron balance

Answer 24

Exhaustion of iron stores
Iron deficient erythropoiesis
Falling red cell MCV
Microcytic Anaemia
Epithelial changes
skin
Koilonychia
Angular stomatitis

Question 25

what is sideroblastic anaemia

Answer 25

excess iron build up in mitochondria (blue granules around nucleus) due to failure to incorporate iron in to haem. Can be hereditary or acquired eg MDS, lead poisoning, alcohol excess

Question 26

how can iron def be confirmed

Answer 26

combo of anaemia - decreased haemoglobin iron and reduced storage iron- low serum ferritin

Question 27

causes of iron overload

Answer 27

Primary Hereditary haemochromatosis Secondary Transfusional Iron loading anaemias

Question 28

hereditary haemochromatosis

Answer 28

Commonest form is due to mutations in HFE gene Decreases synthesis of hepcidin Increased iron absorption Results in gradual iron accumulation with risk of end-organ damage iron build up in liver

Question 29

clinical features of hereditary haemochromatosis

Answer 29

Weakness/fatigue Joint pains Impotence Arthritis Cirrhosis Diabetes Cardiomyopathy

Question 30

treatment for hereditary haemochtomatosis

Answer 30

weekly venesection

Question 31

what might patientd with thalassaemias require

Answer 31

lifelong transfusion

Question 32

treatment of secindary iron overload

Answer 32

Iron chelating agents: Desferrioxamine (subcut or IV infusion)‏ Newer oral agents Deferiprone Deferasirox